ΔE 30.6, loose: different enough that you should pick on purpose. Atramentum Black is a little lighter, much more muted than Drakenhof Nightshade.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 31). Atramentum Black is a little lighter, much more muted than Drakenhof Nightshade.
The same difference applies the other way round: Drakenhof Nightshade is a little darker, much more saturated.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Drakenhof Nightshade on the colour wheel See Atramentum Black on the colour wheel
All matches: Drakenhof Nightshade equivalents · Atramentum Black equivalents